Suspension Data for Possible Upgrade

[GizmoQ]

I actually knocked 5 seconds off my average today and I'm still trying to find the limits of this suspension/tire combination.
Now comes the hardest mod of all: improving my driving skills.

Congrats! 5 seconds off is a great achievement!

Hey Giz 5 seconds don't seem like much time! But then again it depends what that 5 seconds is archiving right!
Sound like your at least heading in the right direction! Keep it move that way great news !!

I guess I should have quantified the art of autocross a little before getting so excited. Autocross is a timed event on a road course laid out in a large parking lot with a hundred or so large orange cones and chalk lines to map out the route. Every course is different but the good clubs always setup a course for the average racer to go from start to finish in 60 seconds. There is no side-by-side racing, but there are usually two or three cars on course at a time (spaced out 20 seconds apart).

I've been struggling with Elwood to get my times under 60 seconds (average). Been to two different driving schools and both times the scenario goes something like this: I drive three sessions, the instructor rides with me giving me pointers on how to get faster each ride. By the third ride he says, "O.K., not bad but you need to work on three things: A,B, & C." I then tell him to drive the course in my car and when he's done he says "Nevermind those three things, you're doing all you can."

Well I wasn't satisfied with average. Taking the schools got me comfortable to really stick it all out there and I got down to 59 seconds. Yesterday my worst time was 57 seconds and my best was 55 seconds. Today, I got my time down to 52 seconds. And remember the two instructors I mentioned earlier... they both came running over to my car to congratulate me on my fastest/smooth run ever! Of course they encouraged me to get another second off that but I only dropped it by .471 seconds by the time we were done for the day.

For another perspective on where I am, the PRO drivers (a couple of which are former National Champions) were only doing the course in 49 seconds. So compared to two months ago, I've made a 70% improvement with these suspension/tire changes. I'm competitive in my class and I'm closing in on the Pro drivers little by little, inch by inch.

 

[klaptrapper]

Suspension upgrade

Hey Giz 5 seconds don't seem like much time! But then again it depends what that 5 seconds is archiving right!
Sound like your at least heading in the right direction! Keep it move that way great news !!


Sent from my iPhone using Tapatalk Thanks Dan

Are you kidding??? 5 seconds in an autocross event is an ETERNITY.! If you were anywhere near competitive before, Giz, Sounds like you have a clear winner now

Rusty 06 "V"

 

[graytoad]

They had an Autocross set up at the Syracuse Nationals this past weekend but we didn't bother: we were there in the 1970 Oldsmobile Rallye 350 (Cutlass) and that thing feels like a Boat going around the corners.....


No good on Autocross for sure but it sure looks great in front of a B15........

 

[GM MUSL]

Replacing front spring and all swaybars

Excellent thread Gizmo! I recently upgraded to a 2006 V from a 2006 base model and decided to upgrade the sway bars. On the Base XLR I had I went to the Z06 sway bars and they worked well for me. This time I decided to go with the ZR1 sways based on your information and since I spotted a problem in the front spring I ordered the ZR1 front spring also. I put the same size tires as the rear all around and thought the ZR1 spring might be better for me as I won't plan to go too low in the front. My question is do you need to follow the installation as per the shop manuals including the use of a spring compression tool or is there an easier way? It looks to me if you take the weight off the suspension it should be easy and not require the shock or control arm disconnection. My concern is does the spring need to be arched with the tool to be installed properly? I noticed both front and rear springs are not centered in the retaining caps and are off center a half inch. I wonder if I need to correct the rear as I was only intending to lower the rear to match the new front ZR1 spring. All the parts are on their way from GMpartshouse.

 

[klaptrapper]

Suspension data

Did you bolt a "V" supercharger to the 4.6 liter northstar engine? Intersting as to how long it will last. Since you are being aggressive with your suspension mods, I assume you plan to stress the engine significantly.

Keep us abreast of your experiences, please.

Rusty '06 V

Excellent thread Gizmo! I recently upgraded to a 2006 V from a 2006 base model and decided to upgrade the sway bars. On the Base XLR I had I went to the Z06 sway bars and they worked well for me. This time I decided to go with the ZR1 sways based on your information and since I spotted a problem in the front spring I ordered the ZR1 front spring also. I put the same size tires as the rear all around and thought the ZR1 spring might be better for me as I won't plan to go too low in the front. My question is do you need to follow the installation as per the shop manuals including the use of a spring compression tool or is there an easier way? It looks to me if you take the weight off the suspension it should be easy and not require the shock or control arm disconnection. My concern is does the spring need to be arched with the tool to be installed properly? I noticed both front and rear springs are not centered in the retaining caps and are off center a half inch. I wonder if I need to correct the rear as I was only intending to lower the rear to match the new front ZR1 spring. All the parts are on their way from GMpartshouse.

 

[GM MUSL]

Did you bolt a "V" supercharger to the 4.6 liter northstar engine? Intersting as to how long it will last. Since you are being aggressive with your suspension mods, I assume you plan to stress the engine significantly.

Keep us abreast of your experiences, please.

Rusty '06 V

I changed the car! The former 2006 XLR base model I owned got the V upgrades, excluding the supercharger. I decided it was best to sell it and purchase a real XLR-V. Now I am upgrading the suspension on the new 2006 XLR-V. It is currently all stock and the only upgrades I will do are bolt on.

 

[GizmoQ]

Excellent thread Gizmo! I recently upgraded to a 2006 V from a 2006 base model and decided to upgrade the sway bars. On the Base XLR I had I went to the Z06 sway bars and they worked well for me. This time I decided to go with the ZR1 sways based on your information and since I spotted a problem in the front spring I ordered the ZR1 front spring also. I put the same size tires as the rear all around and thought the ZR1 spring might be better for me as I won't plan to go too low in the front. My question is do you need to follow the installation as per the shop manuals including the use of a spring compression tool or is there an easier way? It looks to me if you take the weight off the suspension it should be easy and not require the shock or control arm disconnection. My concern is does the spring need to be arched with the tool to be installed properly? I noticed both front and rear springs are not centered in the retaining caps and are off center a half inch. I wonder if I need to correct the rear as I was only intending to lower the rear to match the new front ZR1 spring. All the parts are on their way from GMpartshouse.

WOW! First, congrats on your upgrade to a V.

As stated above, I think the ZR1 springs and sways package is too much for our cars. The balance and handling are significantly enough different that the complete ZR1 suspension equipment package just isn't optimal. I think you're going to have a very rough ride with little improvement or worse handling. Our cars have a loose rearend which a full ZR1 package won't solve. I've gone from a loose rear to a slight push that I know is fixable by lowering the rear ride height. And the ZR1 front spring without upgrading the rear spring could cause other problems, i.e., I just burned through another wheel bearing (my 5th in 2 years) so you might want to get a line on new ones before you need them (I've got Timkens with a lifetime warranty, but we'll see how long they continue to honor that). My Mag-Ride is still learning how to cooperate with the new spring and it is improving, but will never be perfect (I've also been playing with adjusting the Mag-Ride sensors). Without the ZR1 modified Mag-ride shocks, your suspension may be on tilt forever.

I look forward to your impressions on how well your setup works, how it rides/corners, and your long-term parts life (tires, shocks, bearings, ball joints, etc.).

As far as the installation instructions, Doug Doty had a nice write-up here on the forum: https://www.xlr-net.com/forums/cadi...on/5727-hoist-out-shop-surgery.html#post36394. I personally liked the HyperCo procedures and had great results: http://www.hypercoils.com/DOC/C5_Front_Rear_Spring_Installation.doc

No spring compression tool needed. The shocks and control arms do need to be unbolted, just not removed. The spring does not need to be compressed to be installed either. Just take your time, tighten everything a little at a time to ensure everything is centered and properly aligned, then tighten again after another 1-200 miles. I also jack the car up using the pucks and lower it onto a bottle jack under the spring so that I can adjust the ride height bolts. I'm really impressed with the HardBar lowering bolts, and since my rear spring has both OEM bolts seized, I have to buy another spring before I can get my rear end lowered.

If you plan to do any spirited driving, I'd recommend you adjust that rear spring. You run the risk of tearing up the rubber mounting tabs or deforming the mounting brackets or the absolute worse scenario rip the threads out of the mounting tab bolt holes. OBTW, be very, very careful reinstalling the rear sway bar mounting bolts. I crossthreaded one without ever knowing it until I went to add some more dielectric grease and graphite to the bushings to solve a squeak I had.

Good luck with your build.
Giz

 

[GizmoQ]

Are you kidding??? 5 seconds in an autocross event is an ETERNITY.! If you were anywhere near competitive before, Giz, Sounds like you have a clear winner now

Rusty 06 "V"

A pair of C5s got embarrassed today! Got their asses handed to them by a Caddy!!!!!!! They now recognize me as a threat as I was .7 seconds faster than them. I just need more experience.

 

[05 GRAND DADDY]

A pair of C5s got embarrassed today! Got their asses handed to them by a Caddy!!!!!!! They now recognize me as a threat as I was .7 seconds faster than them. I just need more experience.

WOW! YOU GO GIZ !!!
LIKE THE HEAR CADDY KICK ASS!


Sent from my iPhone using Tapatalk
Thanks Dan Gouker

 

[onalaska]

Giz, how does it ride on the highway with all those suspension mods?

 

[Popbigguy]

A pair of C5s got embarrassed today! Got their asses handed to them by a Caddy!!!!!!! They now recognize me as a threat as I was .7 seconds faster than them. I just need more experience.

I remember that "whine" sound!!! Looks good Giz!!!

Chad

 

[GizmoQ]

Giz, how does it ride on the highway with all those suspension mods?

Highway cruising is still quite comfortable. That's why I didn't want to change the shocks. PJ doesn't notice any change at all. I do notice more feedback from the steering and when passing. Its probably more input due to lowering and low profile tires than the suspension. It's in the city (dodging potholes) where the changes are most noticeable. Bumping over just one wheel is jarring because the two are tied so rigidly together. And that front air dam is less than 2" off the ground and it scrapes on everything, speed bumps, driveways, dip in the road , everything.

 

[WB6BBZ]

You know Giz, I was just thinking about how to make my ride softer and decided to buy another set of rims so I could put some softer Vogue 'tyres' on the car for cruising and the OEM rims and Michelin tires for show.(Show & GO)

The reason for the softer cruising tires is, my lady friend that I will be picking up in MS. is having back surgery on the 19th of this month and I want to make sure she is comfortable for the day's drive from her place to BG and back.

I found some really good looking rims on the web at one of the Vogue tyre distributer's that with a total of 4 rims, tyres mounted and balanced with a new set of TPMs were just about $200.00 dollars more than just a new set of Michelin Run Flats.
These rims, look just like the ones in the picture of the 'POSSIBLE' new XLR.
I saw this deal just before we saw the new GM Line-up article and I've been searching for the Vogue site all morning but haven't found it yet.

By the way, GREAT JOB ON THE COURSE TIME.

 

[HarvesterUT]

Giz,

Which exact set-up did you end up using? I saw both ZR1 and Z06 fronts mentioned in various posts. What are you using in the rear? Which sway bars are you using? Also, are you using the OEM V shocks?

 

[GizmoQ]

Giz,

Which exact set-up did you end up using? I saw both ZR1 and Z06 fronts mentioned in various posts. What are you using in the rear? Which sway bars are you using? Also, are you using the OEM V shocks?

ZR1 front springs and sways.
Z06 rear springs and sways.

The reason for the mix is because our car weighs so much more, this helps keep my car balanced with the power and torque I have available.

 

[HarvesterUT]

Any reason why you didn't run ZR1 suspension all around? Did you specifically want to firm the front more than the rear for AutoX or something? Also, did the oem shocks have any issue with the stiffer springs?

 

[GizmoQ]

Any reason why you didn't run ZR1 suspension all around? Did you specifically want to firm the front more than the rear for AutoX or something? Also, did the oem shocks have any issue with the stiffer springs?

I put the ZR1 all 4corners at first to remedy my understeer problem. The ZR1 suspension gave me oversteer. The ZR1/Z06 combo made the car finally neutral, flat, and balanced.

 

[GizmoQ]

Any reason why you didn't run ZR1 suspension all around? Did you specifically want to firm the front more than the rear for AutoX or something? Also, did the oem shocks have any issue with the stiffer springs?

I put the ZR1 all 4corners at first to remedy my understeer problem. The ZR1 suspension gave me oversteer. The ZR1/Z06 combo made the car finally neutral, flat, and balanced.

 

[HarvesterUT]

I put the ZR1 all 4corners at first to remedy my understeer problem. The ZR1 suspension gave me oversteer. The ZR1/Z06 combo made the car finally neutral, flat, and balanced.

Ah, OK. Yes, being more front biased in stiffness is one way to combat oversteer. I noticed that you run 265 square tires - have you ever considered running something like 265/285 to also help with rear traction? Do you find the rear coming loose when going into turns (I'll assume off throttle or staying speed neutral), or when you try to apply throttle on the way out, or both?

 

[GizmoQ]

Ah, OK. Yes, being more front biased in stiffness is one way to combat oversteer. I noticed that you run 265 square tires - have you ever considered running something like 265/285 to also help with rear traction? Do you find the rear coming loose when going into turns (I'll assume off throttle or staying speed neutral), or when you try to apply throttle on the way out, or both?

I tried 285 rears once. Don't remember what the issue was (probably rubbing on fender) and they weren't Sport Cups. The wider rear wheel gives me a bit bigger contact patch and 265 is almost perfect to avoid severe roll under in the turns.